Irish Times Fri Feb 05, 2010 by DICK AHLSTROM, Science Editor
Fri, Feb 05, 2010
DOCTORS HAVE managed to “communicate” with a man diagnosed as being in a permanent vegetative state for the past five years.
The man was able to answer a series of personal Yes or No questions by thought alone, despite being in a vegetative state after a severe brain injury.
The researchers who conducted the experiments now believe that up to 40 per cent of patients with disorders of consciousness may be misdiagnosed, and that many may still be able to communicate with loved ones and doctors despite their condition.
“With further development, this technique could be used by some patients to express their thoughts, control their environment and increase their quality of life,” the researchers said.
A team involving staff from the universities of Cambridge in the UK and of Liege in Belgium joined to study a group of 54 patients with disorders of consciousness. All had experienced severe brain injury and were suffering from disorders of consciousness, a condition that leaves them apparently wakeful but without any conscious awareness.
This included 23 in a vegetative state and another 31 described as in a “minimally conscious” state.
The researchers used functional magnetic resonance imaging to study brain activity. It allows them to watch the brain working in real time, detecting the minute increase in bloodflow to areas where thought is causing activity in the brain. They used well-tested methods to deliver clear brain scan responses. The patients and matched healthy people who acted as controls in the experiment were all asked to imagine standing on a tennis court and hitting tennis balls. Alternatively, they were asked to imagine walking through familiar streets or through the rooms in their houses.
The researchers cued each subject with the word “tennis” or “navigate”. The person would imagine one or the other and then be allowed to rest with the cue “relax” before the next cue was given. Details of their work were published yesterday in the New England Journal of Medicine.
Amazingly, they found that five patients, almost one in 10, showed an active brain response, one controlled by the patients themselves. Four of these were considered to possess the lowest order of consciousness, diagnosed as being in a vegetative state with one in a minimally conscious state.
Importantly, the scans for the brain-injured patients closely matched the patterns seen in the control subjects, showing that patients were noting the cues and then responding appropriately.
The researchers then tried to advance this, again using healthy controls and a single brain-injured patient, one of those diagnosed as in a vegetative state.
Subjects were asked simple autobiographical Yes/No questions, such as “Do you have any brothers?” They were asked to think of playing tennis if the answer was Yes and think of navigating streets or through a house if answering No.
Not surprisingly, the healthy controls achieved a 100 per cent response. Yet the severely brain-injured patient, who had been in a permanently vegetative state for the past five years, was also able to answer his questions accurately.
He correctly answered five of six questions. The sixth was not incorrectly answered – he just did not answer Yes or No, leading the researchers to believe he might not have heard the question, fell asleep or had for some reason lost consciousness. The researchers stressed the importance of their scan technique to search for “undetected awareness” in patients suffering from brain-injury-induced disorders of consciousness.
It could greatly improve diagnosis when combined with existing clinical assessment, they said. More importantly, it could open up an unexpected channel of communication for these patients.